Facet Joint Irritation and Muscle Weakness: What You Need To Know

In my experience as a Clinical Myotherapist at Melbourne Massage and Treatment Myotherapy and Lymphoedema Clinic in Coburg, I often look beyond the area where a person feels pain. Sometimes, the problem is not simply a tight muscle or a local injury. The way a muscle contracts, controls movement or produces force can also tell us something about how the nervous system is working.

To better understand this, let’s use an example: unilateral hamstring weakness, where one hamstring appears weaker than the other. This can become particularly important when someone continues training, lifting weights or performing exercises that require both sides of the body to work together, like a squat.

There are several possible explanations for this presentation. One of them involves the lumbar spine, including irritation of the facet joints and, in some cases, changes that affect the nearby nerve roots.

The important point is that you do not always need to experience numbness, tingling or the typical symptoms of neuropathy to have a problem with muscular control that deserves further assessment.

What are the facet joint?

The facet joints, also known as zygapophyseal joints, are small synovial joints located in the posterior portion of the spine on each side of the vertebrae, and they help guide and control spinal movement.

Facet joints’ role is to contribute to each spinal segment’s stability, together with the intervertebral disc. Therefore, they help manage loads during movements such as bending backwards, rotating the trunk and returning to an upright position.

As with any joints, even facet joints can become irritated if placed under excessive loading, repetitive movements, trauma or degenerative changes that develop over time. Indeed, anyone, in their lifetime, would experience some form of facet joint degeneration.

When a facet joint becomes painful, symptoms may include localised lower back pain, stiffness and pain that refers into the buttock or thigh (Meralgia parestetica).

That said, not everyone with facet joint irritation experiences the same symptoms, and degenerative changes on an X-ray or MRI do not automatically mean those changes cause the person’s pain. Indeed, as we already discussed in other blogs, pain is brain interpratiation of a stressor fact, not only a and not always a response to a “damaged” body tissue.

That’s where, looking at research on facet joint disorders, we can see the importance of combining the clinical presentation with an appropriate physical examination rather than relying on imaging findings alone.

Can facet joint irritation affect a nerve?

The quick answer to the above question is: Yes, it can.

But there is a catch too.

Indeed, a facet joint irritation can manifest itself and refer pain to areas of the body that are far from the facet joint itself, but still not irritating a nerve or a nerve’s root.

So in the first instance, the irritated facet joint produces pain. Therefore, surrounding muscles may become more sensitive, guarded or less effective at producing movement because of pain.

On the other hand, structural changes around the facet joint may reduce the space available for a nearby spinal nerve root, leading to still pain, but also to a lack of motor control and ability to use a muscle.

And again, to identify what is what, we need to go through a tailored assessment, and only via this approach can we get a better clinical understanding of what the root cause of your pain is.

And what is most important to keep in mind is that not everyone experiences all these symptoms together.

Can nerve involvement occur without numbness or tingling?

As briefly explained before, when someone experiences facet joint irritation, as part of their symptoms, they may experience loss of control of a specific muscle or group of muscles. That said, the loss of motor control is not always related to numbness, tingling or burning pain.

So a spinal nerve root contains fibres involved in both sensory and motor functions, and based on the location and severity of the problem, these functions may not be affected equally. Together with active, passive and resisted range of motion, we can then start narrowing down the clinical presentation and any potential facet joint irritation and/or involvement of a nerve compression.

Why unilateral muscle weakness matters?

If someone presents with unilateral muscle weakness, which can happen when there is inflammation at the facet joint along the spine, you may end up compensating during everyday movement or at the gym with the functional side to deliver an action.

Let’s make an example by looking at a hamstring that is not firing, due to nerve impingement via an irritated facet joint.

Let’s take the case of a client who presents at the clinic with a right hamstring group, the muscle in the back of the thigh, which is not firing.

While this person does walk, squat, or does a double-leg hamstring curl, they may notice the impairment. And this is a common presentation when the weakness, given by a non-firing muscle, is not correlated to any form of pain, at least in the targeted muscle.

What happens if you continue training with one weak hamstring?

Now the concern is not that every strength difference will inevitably cause an injury. We know that one side is more efficient at delivering power than the other side; that’s because we are either right- or left-dominant.

The concern arises when a meaningful weakness changes the way someone performs an exercise.

Depending on the movement, this could involve shifting more weight onto the stronger leg, rotating the pelvis or trunk, changing the depth of the movement or modifying how the hips and knees contribute to the lift.

The other side may consequently perform more work than intended. The weaker side may also be exposed to loads it cannot currently manage well.

This is to say that having one side not firing or working as well as it should can lead to injury, but it also can lead to waste of training, as a muscle that can’t perform at its full potential, due to lack of neural stimulation, can not improve.

So the practical message is simpler: if one side has a persistent and unexplained reduction in strength, continuing to train as though both sides are functioning normally may not be the best approach.

How I approach this presentation in myotherapy

At Melbourne Massage and Treatment in Coburg, before deciding what approach may be appropriate for someone’s pain and injuries, I would look into their:

• Symptoms
• Medical history
• Training demands
• Functional limitations
• Goals (short- and long-term)

Those are a few aspects to consider before starting a treatment plan.

And back to the example, if someone presents with unilateral hamstring weakness, I would not focus exclusively on releasing the hamstring.

Depending on the presentation, an assessment may include:

• Lumbar spine assessment: Looking at the person’s symptoms and how spinal movements affect them.
• Muscle strength and control: Comparing the two sides while considering pain, effort and the quality of the movement.
• Hip and lower-limb assessment: Considering whether the weakness may originate from a local muscle, tendon, hip or other lower-limb problem.
• Neurological screening: Where indicated, assessing relevant muscle strength, sensation and reflexes to identify findings that may require medical investigation.
• Functional assessment: Looking at how the person performs relevant movements, such as a hip hinge, squat or single-leg exercise, when it is safe and appropriate.

That’s how we can look into the next step. Then, if with hands-on treatment we don’t see an immediate change in symptoms, or at least a major improvement in a matter of 2 to 3 weeks, where treatment treatment-wise we may have done 2 to 3 sessions, but you spent a minimum of 3 days a week exercising, then it is worth it to refer you to a GP and get some further investigation ongoing.

Because we know that the body has its own healing time, and 3 weeks of no change in symptoms is a red flag.

Should you keep strengthening the weaker hamstring?

Strengthening is the most important activity you can do for your longevity and wellbeing. That said, when a hamstring is not firing due to lack of neural stimulation, just trying to lift heavier and heavier is not the right approach.

So, first things first, we need to address why your hamstring is weak. If we then realise it is a neuromuscular issue, then we need to improve that presentation before the load can start growing. Therefore, the exercises may need to be modified while the contributing factors are addressed, moving from concentric exercises to eccentric exercises (for example).

On the other hand, when there is no indication of a serious underlying condition, and exercise is appropriate, training can be progressed according to your symptoms, strength, control and tolerance.

When should you come for an assessment?

If you are experiencing persistent unilateral weakness, even without shooting pain, or nerve pain, it deserves immediate attention, especially when there is no clear explanation.

That said, I would skip to medical emergency if your symptoms involve things like:

• weakness develops suddenly
• loss of bladder or bowel control
• difficulty passing urine
• numbness around the groin or saddle region
• rapidly progressive weakness affecting one or both legs

Some of those symptoms, if combined, are signs of severe nerve blockage and need immediate medical intervention.

Final thoughts on facet joint irritation

Facet joint irritation is one possible source of spinal pain, and certain associated structural changes can affect nearby nerve roots. However, it is important to distinguish joint-related pain, pain-related muscle inhibition and true neurological weakness.

In clinical practice, I would assess a unilateral weakness in context rather than automatically attribute it to the spine or to a local muscle problem.

Therefore, if you are training regularly and notice that one hamstring or one muscle on one side of the body only is consistently weaker than the other, do not assume that the difference will resolve simply by working harder.

At Melbourne Massage and Treatment Myotherapy and Lymphoedema Clinic in Coburg, I take an individualised approach that considers your symptoms, movement and training goals. Where appropriate, I combine hands-on treatment with targeted exercises, while recognising when further medical assessment is needed.